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Subject[PATCH AUTOSEL 5.2 43/59] arm64/mm: fix variable 'tag' set but not used
Date
From: Qian Cai <cai@lca.pw>

[ Upstream commit 7732d20a160c76006c7fe7bca5178aea6af1d2e8 ]

When CONFIG_KASAN_SW_TAGS=n, set_tag() is compiled away. GCC throws a
warning,

mm/kasan/common.c: In function '__kasan_kmalloc':
mm/kasan/common.c:464:5: warning: variable 'tag' set but not used
[-Wunused-but-set-variable]
u8 tag = 0xff;
^~~

Fix it by making __tag_set() a static inline function the same as
arch_kasan_set_tag() in mm/kasan/kasan.h for consistency because there
is a macro in arch/arm64/include/asm/kasan.h,

#define arch_kasan_set_tag(addr, tag) __tag_set(addr, tag)

However, when CONFIG_DEBUG_VIRTUAL=n and CONFIG_SPARSEMEM_VMEMMAP=y,
page_to_virt() will call __tag_set() with incorrect type of a
parameter, so fix that as well. Also, still let page_to_virt() return
"void *" instead of "const void *", so will not need to add a similar
cast in lowmem_page_address().

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/include/asm/memory.h | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index b7ba75809751e..fb04f10a78ab3 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -210,7 +210,11 @@ extern u64 vabits_user;
#define __tag_reset(addr) untagged_addr(addr)
#define __tag_get(addr) (__u8)((u64)(addr) >> 56)
#else
-#define __tag_set(addr, tag) (addr)
+static inline const void *__tag_set(const void *addr, u8 tag)
+{
+ return addr;
+}
+
#define __tag_reset(addr) (addr)
#define __tag_get(addr) 0
#endif
@@ -301,8 +305,8 @@ static inline void *phys_to_virt(phys_addr_t x)
#define page_to_virt(page) ({ \
unsigned long __addr = \
((__page_to_voff(page)) | PAGE_OFFSET); \
- unsigned long __addr_tag = \
- __tag_set(__addr, page_kasan_tag(page)); \
+ const void *__addr_tag = \
+ __tag_set((void *)__addr, page_kasan_tag(page)); \
((void *)__addr_tag); \
})

--
2.20.1
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